The present invention relates to an alternating current generator for a vehicle and in particular to an alternating current generator in which the ripple component of an output current is reduced.
Recently, the electrical load of a vehicle has been increasing. A high quality power source having less noise or fluctuations such as ripple has been demanded.
Japanese Unexamined Utility Model publication No. Sho 63-17562 discloses a generator in which two Y-connected three-phase armature coils of a prior art welding inductor type generator are disposed on an armature core of the generator, a first one of the coils being angularly shifted by 150 degrees in electrical angle from a second, other, one of the coils. Each three-phase armature coil is connected with respective full-wave rectifiers. The respective rectifiers are connected in parallel with each other.
Two three-phase alternating currents generated by the three-phase armature coils of the above mentioned structure having the 150 degree phase difference in electrical angle are converted into direct currents by the respective full-wave rectifiers. These two direct currents are summed to provide an output current of the generator. In the structure, the ripple of the output is reduced by providing the 150 degree phase difference.
However, it is necessary to provide other slots which are angularly shifted by a given mechanical angle corresponding to 150.degree. in electrical angle to insert therein the first three-phase armature coil in addition to slots into which the second three-phase armature coil is inserted. Accordingly, the number of the slots is double as much as that of usual generators.
Making the number of the slots double in such a manner invites disadvantages of difficulties in inserting the coils due to a decrease in rigidity of the armature core and a decrease in the cross section of the slots. Thus there arises also a problem that design of the armature core, particularly for a compact generator, can not be physically performed.